JPH01247191A - Thermosensitive recording material - Google Patents

Abstract

PURPOSE:To improve light-proofness by adding a specific phenylenediamine derivative to a thermosensitive recording material to be used as a specific divinylphthalide compound as a color developer. CONSTITUTION:Phenylenediamine derivative expressed by formula (2) [R is an alkyl group with 1-8 carbon atoms; as alkoxy-alkyl group with 2-8 carbon atoms, and X<1>, X<2>, X<3> are hydrogen atom; an alkyl group with 1-4 carbon atoms; a halogen atom] is added to a thermosensitive recording material containing a divinylphthalide compound expressed by formula (1) [X is a dimethylamino group or a pyrrolidinyl group] as a color developer. As a result, the light-proofness of a color-developed image is significantly improved by the storing antioxidation effects of the compound of formula (2).

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a heat-sensitive recording material. Heat-sensitive recording materials that use a colorless or light-colored leuco dye as a coloring agent and are heated and brought into contact with an organic acid as a color developer to develop color are widely known, and have already been used in blink, facsimile, and Rahel. and is widely used for various purposes.

The following general formula (1) [wherein X represents a dimethylamino group or a pyrrolidinyl group]. ] The heat-sensitive recording material containing the divinylphthalide compound shown as a coloring agent not only produces a colored image that is black in the visible region, but also has strong absorption in the near-infrared region. It can be used as a recording material for digital character reading devices).

``Prior art'' The performance required for heat-sensitive recording materials is that there is no background coloring in the natural state, excellent color development sensitivity and color density when heated, light resistance of images and background, and storage stability (moisture resistance, plasticizer resistance). However, in reality, it is difficult to satisfy all of these conditions at the same time. This is even more difficult with heat-sensitive recording materials that absorb near infrared rays, and although there is a strong demand for recording materials for OCR, the reality is that no material with sufficient performance has yet appeared to meet this demand.

The thermosensitive recording material containing the divinylphthalide compound of the general formula (1) is disclosed in Japanese Patent Application Laid-open No. 62-243652 and Japanese Patent Application Laid-open No. 62-2.
No. 43653, proposed by the present inventors, the background is almost colorless and the color density of the image is high, so it is easy to achieve the high contrast between the image and the background necessary for machine reading. . In addition, since the coloring hue of the visible part is almost black, there is no need for an extra operation such as mixing a large amount of coloring agents of other hues in order to obtain a black image. It also has other excellent properties such as sharp color development sensitivity.

"Problems to be Solved by the Present Invention" However, the divinylphthalide compound represented by the general formula (1) has insufficient light resistance of images, and there is still room for improvement.

The main technical object of the present invention is to provide a heat-sensitive recording material that overcomes this drawback.

``Means for Solving the Problems'' and ``Actions'' That is, the present invention provides that a phenylphthalide compound represented by the general formula (2) is added to a heat-sensitive recording material containing the divinylphthalide compound represented by the general formula (1) as a coloring agent. This was achieved as a result of further research, based on the knowledge that the addition of diamine derivatives significantly improves the light resistance of colored images.

[In the formula, R is an alkyl group having 1 to 8 carbon atoms; an alkoxyalkyl group having 2 to 8 carbon atoms, XI, X2. X3 represents a hydrogen atom; an alkyl group having 1 to 4 carbon atoms; a halogen atom. ] The reason why light resistance is significantly improved when a phenylenediamine derivative represented by -a formula (2) is added to a heat-sensitive recording material using a divinyphthalide compound represented by general formula (1) as a coloring agent is Although it is not clear, general formula (2)
This is thought to be due to the strong antioxidant effect of the compound.

In addition, the compound represented by general formula (2) can be treated in the same manner as the components such as a color forming agent and a color developer, and then applied together when the components are ground and mixed to form a heat-sensitive layer. (Alternatively, it may be applied separately under or above the heat-sensitive layer.The amount used is not particularly limited, and may be appropriately applied in the range of 10 to 200% based on the compound of formula (1). Just choose.

The compound represented by the general formula (1) according to the present invention can be synthesized as described in the above-mentioned published patent application, and specific examples include the following.

3.3-bis(2-(4-dimethylaminophenyl)-
2-(4-methoxyphenyl)ethynyl24.5,6
．． fuchtrachlorophthalide 3.3-bis(2-(4-
Pyrrolidinylphenyl)-2-C4-methoxyphenyl)ethynyl]-4.5,6.7-titrachlorophthalide The compound represented by the general formula (2) is represented by the following general formula (3) It can be easily synthesized by alkylating or alkoxyalkylating a compound.

[In the formula, x1 to x3 have the above-mentioned meanings. ] General formula (2
) The following are specific examples of the compound represented by:

N, N'-dimethyl-N, N''-diphenyl-p-phenylenediamine N, N'-diethyl-N, N'-diphenyl-p-phenylenediamine N, N'-dipropyl-N, N'-diphenyl- p-phenylenediamine N, N"-diisopropyl-N, N'-diphenyl-p
-phenylenediamine N, N'-dibutyl-N, N"-diphenyl-p-phenylenediamine N, N'-diisobutyl-N, N'-diphenyl-p
-phenylenediamine N, N'-dimethoxyethyl-N, N'-diphenyl-P-phenylenediamine N, N''-jethoxyethyl-N, N'-diphenyl-p-phenylenediamine N, N'~dimethoxypropyl- N,N''-diphenyl-p-phenylenediamine N,N'-jethoxyprobyl-N,N'-diphenyl-p-phenylenediamine N,N''-dimethyl-N,N'-di-4-methylphenyl- p-phenylenediamine N, N''-dimethyl-N, N'-di-3-methylphenyl-P-phenylenediamine N, N'-dimethyl-N, N'-di-2-methylphenyl-p-phenylenediamine N, N'-dimethyl-sucrose, N'-di-4-chlorophenyl-p-phenylenediamine N, N'-dimethyl-N, N'-di-3-chlorophenyl-p-phenylenediamine N, N'-dimethyl-N, N'-di-2-chlorophenyl-p-phenyl〉'diamine N, N''-dimethyl-N-phenyl-N' = 4-methylphenyl-p-phenylenediamine N, N'-dimethyl-N-phenyl-N' -4-chlorophenyl-p-phenylenediamine N,N'-dimethyl-N-4-chlorophenyl-N"-
4-methylphenyl-p-phenylenediamine N, N'
-diethyl-N-phenyl-N-4-methylphenyl-p-phenylenediamine General In producing a heat-sensitive recording material using a divinylphthalide compound represented by (1) as a coloring agent, for example, The known method described in Japanese Patent Publication No. 45-14039 can be employed, and the coloring agent may be used alone or in combination. In addition, in order to improve the appearance of the color, color density, image stability, etc., known color formers that develop various hues can be used in combination without impairing the performance of the compound according to the present invention.

For example, 3,3-bis(aminophenyl)-6-aminophthalide, 3,3-bis(indolyl)phthalide, 3-7
Minofluorane, aminobenzofluorane, 2,6-cyamitsufluorane, 2,6-diamitu-3-methylfluorane, spiropyran, phenothiazine, phenoxazine, leukoolamine, diarylcarbazolylmethane, 3-indolyl-3-( aminophenyl) phthalide,
It is used in combination with a coloring agent having a basic skeleton such as 3-indolyl-3-(aminophenyl)azaphthalide, triaminofluorene phthalide, and tetraminodivinylphthalide.

As binders for producing heat-sensitive recording materials, polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, gum arabic, gelatin, casein, starch, polyvinylpyrrolidone, styrene-maleic anhydride copolymer, etc. can be used.

As a color developer, p-hydroxybenzoic acid methyl ester, P-hydroxybenzoic acid hensyl ester, 2.2-
Bis(p-hydroxyphenyl)propane (bisphenol A), 3,4'-isopropylidenediphenol, 2,2-bis(p-hydroxy-m-allylphenyl)propane, bis(4-hydroxyphenyl)acetic acid, 1
．． 1-bis(4-hydroxyphenyl)butyl acetate, 4
,4゛-cyclohexylidene diphenol, 4,4゛-
Thiodiphenol, bis-(4-hydroxy-3-methylphenyl) sulfide, bis(4-hydroxy-3
-tert-butyl-6-methylphenyl) sulfide, 4,4'-dihydroxydiphenyl sulfone, 4-
Hydroxy-4'-methyldiphenylsulfone, 3.4
-dihydroxy-4”-methyldiphenylsulfone, 4
-Hydroxy-4'-isopropoxydiphenylsulfone, 4,4''-dihydroxy-3,3'-dimethyldiphenylsulfone, 4,4'-dihydroxy-3,3'-
Diallyldiphenylsulfone, dimethyl 4-hydroxyphthalate, 1,3-di(4-hydroxyphenylthio)
Propane, 1.5-di(4-hydroxyphenylthio)
Pentane, 1,5-cy(4-hydroxyphenylthio)
-3~Oxabencune, 1,7-di(4-hydroxyphenylthio)'-3,5-dioxahebutane, ■, 8-
Di(4-hydroxyphenylthio)-3,6-thioxaoctane, bis(4-hydroxy-3-methylphenyl) sulfide, 1-benzyl-2-naphthol, 1゜1''-methylene-di-2-naphthol, Hydroxy compounds such as p-hydroxyphenyl salicylamide, 1.3
-diphenylthiourea, 1,3-ditolylthiourea,
1,3-dichlorophenylthiourea, zinc benzoate, zinc nitrobenzoate, zinc chlorobenzoate, zinc salicylate, zinc salicylate derivatives, etc. can be used alone or in combination.

Sensitivity improvers include known paraffin wax, carnauba wax, higher fatty acid amide, higher fatty acid ester, dibenzyl oxalate, di-P-chlorobenzyl oxalate, phthalate ester, terephthalate ester, benzyl 4-benzyloxybenzoate, 1-hydroxy -2-naphthoic acid ester, 2-hydroxy-3-naphthoic acid ester, naphthol benzyl ether, 1,4-dialkoxynaphthalene, 1,5-dialkoxynaphthalene, 1-phenoxy-2-naphthoxy(1)ethane, 1 .2-di(3-methylphenoxy)ethane, 1-(2-isopropylphenoxy)-2-naphthoxy(2)ethane, bis(p-methoxyphenoxyethyl)ether, hydroquinone dibenzyl ether, 4,4''-di Alkoxydiphenylsulfone, m-terphenyl, p-benzylbiphenyl,
Dibenzylbenzene, penzamide, diphenylamine, benzenesulfonamide, benzenesulfonanilide, toluenesulfonanilide, diphenyl carbonate, etc. can be used alone or in combination.

Further, an overcoat such as a polymer material is also an effective means for improving the light resistance and moisture resistance of an image.

"Examples, etc." Next, the present invention will be specifically explained by giving examples of the production of heat-sensitive recording paper as examples, as well as comparative examples, and further showing comparative tests. (In the following, parts represent parts by weight.) Production Example 1 1) Preparation of color former dispersion (liquid A) Kaolin 15 parts 10% polyvinyl alcohol aqueous solution 100 parts water
85 parts The above mixture was pulverized using a paint shaker (manufactured by Toyo Seiki Co., Ltd.) until the average particle size of the color former was 1 micron.

2) Preparation of color developer and dispersion (liquid B) Bisphenol A 15 parts Zinc stearate 10 parts 10% polyvinyl alcohol aqueous solution 150 parts The above mixture was ground in a paint shaker until the average particle size was 2 microns.

3) Preparation of phenylenediamine derivative dispersion (C? (1) N, N'-dimethyl-Ill, N'-diphenyl-p
- Phenyl diamine 3 parts 10% polyvinyl alcohol aqueous solution 8 parts water
4 parts The above mixture was ground in a paint shaker to an average particle size of 2 microns.

4) Preparation and Coating of Heat-Sensitive Coating Liquid 10 parts of liquid A, 6.5 parts of liquid B, and 2 parts of liquid C were mixed and stirred to obtain a heat-sensitive coating liquid. This coating liquid was evenly applied to paper using a wire bar so that the weight after drying was 6 g/m, and then dried to obtain heat-sensitive recording paper.

This thermal recording paper had no background fog and was almost colorless, and quickly developed a deep black color when heated with a thermal pen or the like. Furthermore, OCR has strong absorption at 700 to 11000n.
It was possible to read by

Furthermore, the coated surface also had excellent light resistance, and no coloring occurred due to sunlight irradiation.

Production Example 2 In preparing liquid A of Production Example 1, 3.3-bis[2-(p
-dimethylaminophenyl)-2-(p-methoxyphenyl)ethynyl) -3,3-bis[2-(p-pyrrolidinylphenyl)-2 instead of 4,5,6,7-tetrachlorophthalide A thermosensitive recording paper was obtained by using -(p-methoxyphenyl)ethynyl)-4,5,6,7-tetrachlorophthalide and otherwise operating in the same manner as in Production Example 1.

Production Example 3 In preparing liquid C of Production Example 1, N, N'-dimethyl-
N,N'-dimethyl-N,N'-di-4-methylphenyl-p-phenylenediamine was used instead of N,N'-diphenyl-p-phenylenediamine, and the rest was Production Example 1.
A thermosensitive recording paper was obtained in the same manner as above.

Comparative Example 1 In preparing liquid C of Production Example 1, N,N'-dimethyl-N
, N''-diphenyl-p-phenylenediamine was not used, and the other operations were the same as in Production Example 1 to obtain a thermal recording paper.

Comparative Example 2 In the preparation of liquid C of Production Example 2, N,N''-dimethyl-N
, N'-diphenyl-p-phenylenediamine was not used, and the other operations were the same as in Production Example 2 to obtain a heat-sensitive recording paper.

Comparative Test The light resistance of the heat-sensitive recording papers obtained in the above production examples and comparative examples was tested by the following method. The results are shown in Tables 1 and 2, respectively.

Lightfastness test Each thermal recording paper was colored using a thermal coloring tester (manufactured by Matsushita Electronic Components Co., Ltd.) at an applied voltage of 16 V and a pulse width of 3.5 milliseconds. Test this colored image using a fade tester (■
After exposure for 3 hours using a CF-2ON model (manufactured by Shimadzu Corporation, light source Carbon Arrive), the reflection density at 900 nm was measured using a spectrophotometer (model ① UV-365, manufactured by Shimadzu Corporation).

The image survival rate was determined using the following formula, and the light resistance was determined.

Table 1 Table 2 The above test confirmed that the heat-sensitive recording paper of the present invention has extremely excellent light resistance.

"Effects of the Invention" The heat-sensitive recording material of the present invention is a heat-sensitive heat-sensitive recording material for OCR because it produces a black colored image, which is in high demand, has strong absorption in the near-infrared region, and has extremely excellent light resistance. It has high industrial utility value.

Claims (1)

[Claims] 1) A heat-sensitive recording material using a divinylphthalide compound represented by the general formula (1) as a coloring agent,
A heat-sensitive recording material characterized by containing a phenylenediamine derivative represented by 2). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) [In the formula, X represents a dimethylamino group or a pyrrolidinyl group. ] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) [In the formula, R is an alkyl group having 1 to 8 carbon atoms; an alkoxyalkyl group having 2 to 8 carbon atoms is represents a hydrogen atom; an alkyl group having 1 to 4 carbon atoms; a halogen atom. ]